


To Be A Master

by artikgato



Category: Persona 4, Pocket Monsters | Pokemon (Main Video Game Series)
Genre: Alternate Universe, M/M
Language: English
Status: Completed
Published: 2021-02-27
Updated: 2021-02-27
Packaged: 2021-03-18 20:13:44
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 7,435
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29739258
Author URL: https://archiveofourown.org/users/artikgato/pseuds/artikgato
Summary: Former Kanto champions Yosuke Hanamura and Yu Narukami are called in to Cerulean City to help fight a strange and powerful Pokémon inside the nearby Cerulean Cave, and they end up getting way more than they bargained for.
Relationships: Hanamura Yosuke/Narukami Yu, Hanamura Yosuke/Persona 4 Protagonist, Hanamura Yosuke/Seta Souji
Comments: 5
Kudos: 39





	To Be A Master

**Author's Note:**

> Happy Pokémon Day everybody! Pokémon Red and Green version were released in Japan 25 years ago today. I wanted to do something special to celebrate, and my brain naturally went "Souyo Pokémon au? Souyo Pokémon au." So here's the Souyo Pokémon AU nobody asked for but I'm sure as heck delivering!
> 
> I played a little fast and loose with some rules of the Pokémon universe in this one, such as:
> 
> -Trainers can have more than 6 Pokémon with them and use them freely. The 6 rule only applies to battles against other trainers. I feel like this should be a thing in all the games, imho  
> -Pokémon can know more than 4 attacks, and again the 4 moves rule only really applies to trainer battles. Also I swear the Mewtwo that was in Max Raid battles in SWSH had more than four attacks anyway...  
> -Most trainers can only command one or two Pokémon at a time, but very good/experienced trainers can command up to three (because of the existence of triple/rotation battles)  
> -Trainers can use Pokémon loaned to them from other trainers without there needing to be a trade, if the Pokémon likes/trusts the other trainer enough
> 
> Anyway, that's enough of that. Enjoy the fic!

Yosuke didn’t understand how, but Yu just always seemed to be one step ahead of him. Every Gym he arrived at, Yu’s name was already in the list of recent victors. Every new town he arrived in, the silver-haired guy would inevitably already be there, offering a friendly wave and challenging him to a Pokémon battle. The one that had stung the most was fighting his way tooth and nail through the Elite 4, only to enter the Champion’s chamber to find not Lance as he had been expecting, but Yu  _ freaking _ Narukami there waiting for him. 

It would have,  _ should  _ have been so easy to hate him, except that he was so dang  _ nice _ to Yosuke. He didn’t gloat when he won, he just smiled and said he still had a lot to learn whenever Yosuke won. He’d wholeheartedly congratulated Yosuke on his victory over him when they’d fought in the Champion’s chamber. His smile was infectious, not to mention he was really, really handsome. Yosuke  _ wanted _ to hate him, but he was starting to suspect that rather the opposite was happening…

This time, though, this time he didn’t mind that Yu was one step ahead of him. It was reassuring to see him amidst all the chaos. He’d never seen the skies above Cerulean City so dark, and it was unnerving him just a little bit. 

“So, how bad is it?” Yosuke asked as he joined Yu on the Nugget Bridge, staring westward. Cerulean Cave’s entrance looked like a yawning portal to hell, if he was being honest. He was glad he’d brought along a Pokémon that could use Flash.

“Bad enough that they called us in,” Yu replied, flashing an uneasy grin over at him. “I was all the way on the top of Mount Silver when I got the summons.” 

“What were you doing there?” Yosuke asked, incredulous. 

“Training,” Yu simply replied.

“I had to close the gym to come here,” Yosuke said.

“Lance and the Elite 4 are already inside. They said they’ll send a messenger Zubat if they need our help,” Yu informed him, and Yosuke scoffed.

“I didn’t close my gym to be on  _ standby _ ,” he said. He pulled a Pokéball off of his belt. “I’m going in.” 

“My thoughts exactly,” Yu said, also producing a Pokéball. Yosuke flashed a cocky grin at him and Yu returned it. 

“Let’s go, Gyarados!” Yosuke exclaimed, tossing the Pokéball into the air. With a flash of light his Gyarados appeared, splashing down into the water beside the bridge. 

“I choose you, Gyarados,” Yu said, coolly. He had a glimmer of mischief in his eyes, and Yosuke wasn’t as surprised as he should have been when Yu’s Gyarados turned out to be red instead of blue. He just sighed.

“Of  _ course _ you managed to find a shiny,” he grumbled. He may have sounded bitter, but he was happy for and proud of his friend. Even though he’d shown Yosuke up yet  _ again _ . When they’d had their climactic battle for the Champion title he’d impulsive declared them to be equals. After all, Yosuke had barely won the fight. It had all come down to their starter Pokémon. Yosuke had been at a disadvantage when he’d sent out his Venusaur against Yu’s Charizard, but he and Venusaur had somehow managed to pull through and barely edge out a win. Yu always had underestimated poison.

Yosuke had been promptly unseated by some upstart from Johto not long after, but that suited him just fine. He was perfectly content being a Gym Leader now. Still, he and Yu were considered to be roughly equal in terms of battle prowess and fighting strength. He had a feeling that they were about to find out just who was stronger in this cave. He also knew that Yu had ways of showing him up that had almost nothing to do with battle prowess. Like the freaking shiny Gyarados.

“I bred for him, actually,” Yu remarked, stepping up onto the railing of the bridge and hopping onto his Gyarados’ head. Yosuke did the same.

“Of course,” Yosuke repeated. “And let me guess, there’s a route in Johto that’s just teeming with unnaturally strong Magikarps now.”

“I mean, most water routes are teeming with Magikarp, Yosuke,” Yu replied. Yosuke shook his head. 

“Well, I’m looking forward to seeing the rest of the team you brought with you,” he said. With that they both headed for the opening of the cave. The last time Yosuke had seen it, there had been a small patch of dry land in front of the cave. Something, whatever it was that the Elite 4 and current Champion were fighting inside, had evidently obliterated the bit of land and made the cave entrance much, much bigger. 

The inside was almost as much of a mess as the outside was. Water and rubble was everywhere, and judging from the rumbling he could hear coming from below, the fight was taking place below ground. 

“We need to find a way to get underground,” Yu informed him. 

“Yeah,” Yosuke agreed. “Think there’s a natural way, or will we have to dig one ourselves?”

“That could be dangerous. Let’s look for a way down,” Yu replied. He produced another Pokéball, and in the dim light from the outside, Yosuke could tell it wasn’t the standard kind you could just buy at any old Mart. It was green, but aside from that Yosuke couldn’t make out any other details. 

“Hey, what kind of Pokéball is that?” he called over to Yu.

“It’s called a Friend ball,” Yu explained. He tossed it into the air and out came a Crobat. “It makes Pokémon friendlier toward you.”

“And where the heck did you get it? I’ve never heard of anything like that!” Yosuke demanded.

“A friend of mine in Johto named Kurt makes them out of these nuts called Apricorns,” Yu said. “If you can spare some time away from the gym, I’d be happy to introduce you to him.”

“Wait, I think I might have heard of him,” Yosuke said. He reached for a Pokéball of his own. He watched as Yu’s Crobat flew away after Yu spoke a few words to it that Yosuke couldn’t quite make out. “Hey, if I use Flash is that going to make it harder for your Crobat to see?” 

“Yeah, probably. Give her a few minutes to see if she can find a way downstairs,” Yu called back. “We can stay near the entrance for now.” There was a tremor from underground intense enough that Yosuke could feel it all the way up on Gyarados’ head. “It’s...probably safer that way.” 

“I’ll say,” Yosuke replied. He put the Pokéball away with a frown. A few minutes and a couple more tremors later, the Crobat returned. She circled Yu’s head a couple of times, excitedly.

“I think she’s found a way down,” Yu called, and Yosuke nodded in response.

“Lead the way, then!” he said. Yu nodded to the Crobat, and she took off further into the cave. Yu instructed his Gyarados to follow her, and Yosuke followed on his own Gyarados. Yosuke was glad that Gyarados was a Pokémon that could traverse both water and land, because there was  _ so  _ much debris. What had probably once been a river was a bunch of disconnected pools of water and a waterfall that flowed down into the underground through what looked like a huge crater. Judging by the amount of debris and the sharp, jagged edges, said crater was not natural. Looking at the carnage, it only then struck Yosuke that there weren’t any wild Pokémon around. It was eerie, and way too quiet.

Yu recalled the Crobat and without even checking in with Yosuke at all, he and his Gyarados descended down the waterfall.

“Wha- hey!” Yosuke exclaimed. Yosuke told his own Gyarados to go down the waterfall, but he refused. “You can’t do it? Ugh, but Yu’s Gyarados could… must be some trick he picked up in Johto. Alright, that’s fine. Set me down on the ground, okay?” His Gyarados did just that, lowering his head down so that Yosuke could jump down and recall him. Yosuke then called out his Pidgeot and Jolteon. He had the Jolteon light up their surroundings with Flash, and he climbed on the back of Pidgeot with Jolteon in his lap. Together they descended down into the crater, spotting Yu and landing beside him. Yu had recalled his Gyarados in favor of his Raichu, which was also using Flash. There wasn’t much to see, though: more rubble, more puddles, huge boulders. Something on the other side of the cave was giving off an eerie purple glow, though, and Yosuke was more than willing to bet that was where they were heading.

“Did anybody actually tell you what we’re facing down here?” Yosuke asked as he recalled Pidgeot. Yu shook his head.

“No, all I was told was to bring my strongest Pokémon,” he replied. Yosuke nodded. That was all the information he’d been given as well. “When I arrived, Cerulean City had already been evacuated.”

“Yeah, Chie told me. Honestly, it was her frantic texting that made me realize how serious the situation is,” Yosuke replied. “She wanted to stay and help, but Lance told her she needed to stay with the residents, in case whatever this thing is manages to get out.” 

“So, how should we do this?” Yu asked. “A stealthy approach might be best, but it’s going to take forever to get across all this debris.” 

“Leave that to me, Partner,” Yosuke said. Yu turned to him and raised an eyebrow. 

“Partner?” he asked.

“Well, we’re working together for once, so I kinda figured… uh, n-nevermind,” Yosuke stammered, but Yu grinned. 

“No, no, I like it,” Yu replied. “Alright, then, shall we, Partner?” Yosuke couldn’t help grinning, and if there was some heat in his cheeks he could always blame it on the weird lighting, right? Without further ado he reached for his belt.

“Go, Poliwhirl!” he said, and with a flash his trusty Poliwhirl appeared. “He can take care of all the debris in our way, and I can use him to cross any of the water. A lot less flashy than Gyarados, right?” 

“Good idea,” Yu said. Yosuke briefly wondered if Yu had brought along any other Pokémon that could Surf aside from the red Gyarados, but it was  _ Yu _ he was talking about,  _ of course _ he had.

Even with Poliwhirl clearing the way, the trek was still a bit treacherous. Even with both Jolteon and Raichu lighting the way, it was still far too easy to step in the wrong spot and cause a rock slide, but fortunately Yosuke’s Poliwrath was both strong  _ and _ fast and was able to Mega Punch all the rocks away. All the while, the purple glow was getting bigger and bigger as they got closer to it. The tremors had stopped, but that almost worried Yosuke more than if they had continued. In all likelihood a battle had been taking place, and the lack of tremors meant that the battle had likely ended… and probably not in the favor of the Elite 4 and Champion. 

As they got closer, their fears were all but confirmed. They came across Bruno first. The muscular man was leaned up against a rock, unconscious but fortunately still alive. They found Koga not too far away in a similar state. Will was next, and though he wasn’t unconscious he looked like he was on the verge of it.

“It’s powerful,” Will wheezed at them. “Its psychic powers far exceed my own and those of my Pokémon. Even Sabrina would be no match for him.”

“Aw, man! Why didn’t anyone tell me we’d be up against a psychic type?!” Yosuke groaned. Most of his Pokémon were poison types, or fighting types, not to mention the poison/fighting type. He was screwed. Yu looked a little worried as well. 

“What exactly is it?” he asked. Will shook his head.

“Lance mentioned some kind of experiments, but I don’t really know. I don’t think it’s a natural Pokémon. Karen doesn’t think so either,” he said.

“Where is she?” Yosuke asked. 

“She’s further in, with Lance,” he answered. “Her dark-types were holding their own against the thing. I don’t know if she’s still fighting it, but the ground stopped shaking so I’m going to go ahead and guess that she isn’t.” 

“Hang in there,” Yu said. Will nodded. He had a Natu in his lap who looked battered, but it at least had enough HP to be using Flash to light up the area. Yosuke and Yu recalled their own electric types, hoping there would be enough ambient light to see. They cautiously crept forward, Yosuke keeping Poliwrath at the ready despite knowing the poor frog was weak to psychic attacks. 

Yosuke would have expected things to get darker as they moved further away from Will and his Natu, but to his surprise they didn’t — they just took on a distinctly purple hue.

They found Karen a little further toward the purple glow. Like Will she was still awake, but barely. 

“It’s strong,” she said, unintentionally copying what Will had said. “My Dark types resisted its Psychic attacks just fine, but it has other types of attacks. Electric, ice, fire… it even used a Hyper Beam. Be careful. It could know just about anything.” 

“Well, that’s comforting,” Yosuke joked. Karen glared at him. She hadn’t been in the Elite 4 in Yosuke’s day, she was a newcomer. A newcomer who, apparently, had little respect for a former Champion. 

“Be careful,” she told Yu, who nodded. She looked at Yosuke’s Poliwrath. “And I’d suggest you put him away. Seriously, it might be strong enough to kill a Pokémon that’s weak to it. Bruno’s fighting types and Koga’s poison types didn’t stand a chance, it wiped them all out with one attack. All at once.”

“That’s alarming,” Yu said, and Yosuke nodded. He reluctantly recalled Poliwrath, and the two of them moved on. After a few minutes of steadily, slowly creeping, Yosuke sighed.

“I don’t think I’ll be much use here,” Yosuke admitted, quiet. Yu stopped and turned back to look at him. “The only Pokémon I brought along that are fully trained that aren’t weak to psychic are Pidgeot, Jolteon and Gyarados.”

“You always did favor Poison types,” Yu said, with a frown. “But, look, if this thing is as strong as I think it is,  _ any _ help is better than no help.” Yosuke also frowned. 

“Yeah...I guess,” he said. “I have two pure water types with me, but they’re under-leveled. I don’t want to risk them getting really hurt fighting this thing. And I think if I send Toxicroak out it’ll get vaporized.” 

“That’s the frog from Sinnoh, right?” Yu asked. “The poison/fighting type? Yeah, I can see why you’d be so hesitant…”

“We still haven’t found Lance. He could still be fighting…” Yosuke suggested, but he trailed off, lamely. The cavern was eerily quiet. There was no way a Pokémon battle was happening, they’d hear it otherwise. Yosuke could admit it, he was very nervous. But Yu wanted him to come along, so that’s what he was going to do. He had his reputation as a former Champion to uphold, after all. 

As they progressed forward, they started to find huge gashes in the rubble and the floor of the cavern. Yu bent down to inspect one.

“Hyper beam,” he said. “Must have been one of Lance’s Dragonites.” 

“Dang,” Yosuke swore. “If even Lance couldn’t take this thing out… do you think we stand a chance?”

“Maybe. But we’re not the only Champions that got called in,” Yu pointed out.

“Should we wait for backup?” Yosuke asked. Yu shook his head.

“We can’t risk whatever this thing is getting out of the cave. Think of the damage it could do to Cerulean City, not to mention the rest of Kanto,” Yu replied. Yosuke sighed.

“When you’re right, you’re right,” he said. “Alright. Man. When I told you I’d follow you to the ends of the Earth I didn’t ever think I’d mean it literally…”

They found Lance in a similar state to Karen and Will: worse for the wear and exhausted, but not unconscious.

“Oh good,” he said, with a cough. “The calvary has arrived.”

“Anything you can tell us about what we’re facing?” Yu asked, kneeling down beside the prone dragon master. Yosuke kneeled down on the other side of him.

“It says the name it was given is Mewtwo,” Lance said. Yu gasped, and Yosuke looked up at him, startled.

“Know something I don’t, Partner?” he asked. Yu nodded.

“I’ve heard rumors… well, I guess they’re more like legends, really… about the mythical ancestor of all Pokémon, Mew. For this thing to be saying it’s called Mew _ two _ …” Yu trailed off. Lance nodded, looking grim.

“It looks like a lab experiment gone wrong. Horribly wrong. I’d been hearing about supposed genetic experiments happening on Cinnabar Island, in that mansion that burned down, but Blaine never said anything about it,” Lance said. He groaned. “Some Champion of Kanto I am. The two of you are much better leaders than me. One of you should really take up the mantle again.”

“I’ll think about it,” Yu said, looking up at Yosuke with a pensive smile. 

“Me too,” Yosuke said. “But you’re a perfectly fine Champion, Lance.”

“Heh,” Lance replied. “Well, let’s discuss this after you two go save the world. I’m completely tapped. The thing, the Mewtwo… it’s really powerful. It mostly uses Psychic power, but it is absolutely a master of many different attack types. It knew to use ice moves against my team. It was able to take out Karen’s team with fighting type moves. Will and the rest all fell to its psychic type attacks. Be on your guard. We managed to weaken it somewhat, but not by much, I’m afraid.” 

“We’ll do our best,” Yu said. He looked up and locked eyes with Yosuke. “Right, Yosuke?” Yosuke simply nodded. Yu started to stand, but Lance reached up and grabbed his wrist.

“Wait,” Lance said. With his other hand he pulled a Max Potion out of his pocket and pressed it into Yu’s hands. “My Pokémon were taken out before I could use this, and I don’t have any Revives. Use it well.”

“I will,” Yu promised.

Lance’s description of the Mewtwo had been apt, but it hadn’t prepared them for what it actually looked like. It was floating several feet off of the ground, surrounded by that purple glowing aura, eyes closed and in a meditative pose. It looked like a cat… sort of. It had the head shape of a cat, at least, and its arms and legs ended in what looked like paws… sort of. A long tail hung below its form. The two of them were far away, tucked behind a boulder and cautiously peering at the Mewtwo around the edge of it. Yosuke was fairly sure it hadn’t seen them, but was proven wrong when its eyes suddenly opened and a surprisingly deep voice boomed in his head.

“More challengers?” the voice asked. One look at the wide-eyed Yu confirmed to Yosuke that he had heard the voice too. “Why can you humans not leave me in peace?”

“Stay here,” Yosuke heard Yu whisper, and he could only watch, flabbergasted, as Yu stepped out from behind the boulder.

“What are you  _ doing _ ?!” he hissed. Yu ignored him. He walked until he had a direct, uninterrupted line of sight with the Mewtwo.

“I’m afraid you are far too powerful to be left here unchecked, my friend,” Yu called. “You are a danger to the world with your powers, whether or not you realize it.”

“Danger to the world?!” the Mewtwo scoffed. “I simply wish to be left alone, is that too much to ask? You humans made me this powerful. I didn’t  _ ask _ to be like this.” 

“I am sorry to hear that,” Yu said. “And I am sorry that we must fight. I’ve been told that you are very powerful, so I won’t be going easy on you.” Yosuke watched as Yu gathered Pokéballs in his hands. He knew Yu’s Pokémon were powerful, but he was still worried. Despite what Yu said, he stepped out from behind the boulder. 

“I know two against one isn’t fair, but we aren’t playing around here,” he said, readying the Pokéballs containing Gyarados, Pidgeot and Jolteon. 

Yosuke was expecting the Mewtwo to be angry or even frustrated, but to his surprise it started laughing instead.

“Finally, a challenge!” the Mewtwo said. Yu called out not one, not two, but three of his Pokémon, and Yosuke hastily followed. 

The battle was pure chaos. Commanding three Pokémon at once was a challenge during normal circumstances, but coordinating with Yu’s three Pokémon and against such a powerful foe was very difficult. Yosuke told his Jolteon to help Yu’s Raichu, and together they sent a blindingly powerful double Thunder crashing down on the Mewtwo. He and Yu also managed to coordinate their Gyarados together, Yu’s going right and his going left and both of them firing powerful Hydro Pumps at the creature. Pidgeot flew high and attacked with a Hurricane, while Yu’s Rhydon sent rocks crashing down on the Mewtwo. With a blast of purple energy, the Mewtwo blew the rocks away, unscathed. None of those attacks looked like they had phased him in the slightest. The Mewtwo's eyes glowed with that purple energy, and it sent a wave of psychic power out in all directions.

“This is bad,” Yu said, watching their Pokémon stagger in the wake of the psychic blast. Yosuke watched in horror as his Pidgeot plummeted out of the sky, only to shake off the attack and right herself at the last minute, barely managing not to slam into the rocky floor of the cave. 

“What should we do?” Yosuke asked. Jolteon already looked hurt. He was a glass cannon, not built to take hits. 

“Just keep attacking, what else can we do?” Yu asked. 

Jolteon and Raichu sent another powerful Thunder at the Mewtwo, only for it to shrug it off. Both Gyarados fired Hyper Beams, which the Mewtwo somehow deflected, sending them careening away, creating yet more gashes in the cave floor. Pidgeot whipped up another Hurricane, and Yu’s Rhydon charged the Mewtwo at full speed. Just before Rhydon could hit, the Mewtwo lifted a hand and purple energy circled around Rhydon, sending it flying away to slam into one of the cave walls. The two Champions watched as Yu’s Rhydon fainted, returning to Yu’s Pokéball in a flash of red energy. Yu grimaced. Before he could send in a replacement, the Mewtwo struck again, this time sending two bolts of thunder crashing into both Gyarados. They were recharging from the Hyper Beams, so they couldn't even dodge. Both fainted as well, returning to their Pokéballs.

Yosuke started to panic.

“I think we’re in over our heads here,” he said. Yu turned to him and gripped him by the shoulder.

“Focus, Yosuke,” he said. “We need to work together to beat this thing!” Jolteon and Raichu barely managed to leap out of the way as a blast of psychic energy literally left a crater where they had been standing. They blasted Mewtwo with yet more electricity, and Pidgeot desperately sent another Hurricane careening into the Mewtwo. Instead of taking the hits, the Mewtwo used some kind of enhanced Reflect to send the attacks flying away. Lightning and wind swirled around the cave. Yosuke and Yu both ducked behind the boulder to keep from getting hit. Pidgeot mercifully fainted in mid-air and returned to her Pokéball before she hit the ground. Jolteon and Raichu also fainted, having been blown away into a large pile of rubble. 

“Crap,” Yosuke muttered. Yu turned to him and held out a Pokéball.

“Yu?” Yosuke asked.

“He’ll listen to you, don’t worry,” Yu simply said. He pulled the bag off of his back and withdrew three Ultra Balls, tucking away the Pokéballs of the fainted Pokémon.

“What are you doing?” Yosuke asked.

“So much for the power of Champions,” they heard Mewtwo’s voice boom through the cave. Yu sighed.

“I didn’t want to have to use these three, but I guess I’ve got no other choice. Back me up, okay?” Yu requested.

“What are you talking about?” Yosuke asked. Yu stood and left the shelter of the boulder, again facing Mewtwo head-on with the three Ultra Balls in hand. Yosuke scrambled to reach into his bag. He wasn’t about to just let Yu have all the glory. Even if sending out a part fighting or poison type was basically suicide, he wanted to know he’d done everything he could to help fight this creature. 

“Come forth, Legendary birds!” Yu called, tossing the three balls into the air. To Yosuke’s utter shock, three birds emerged from them that he’d only ever seen depicted in ancient artworks or artists' renditions. Elegant blue Articuno, stunning yellow Zapdos and fiery red Moltres emerged, surging up into the air. Yosuke’s jaw hit the floor.

“You captured the  _ legendary birds _ ?!” he squawked. Yu smirked over at him.

“What, like it’s difficult?” he taunted. Yosuke glared at him for a second, huffed out a sigh, and called out his Poliwrath, Venusaur, and — as he’d suspected — Yu’s Charizard.

Yu commanded the birds to blast Mewtwo with Ice Beam, Thunder Bolt and Flamethrower until either Mewtwo fainted or they did. Yosuke prayed that Mewtwo would be too distracted by them to notice his Venusaur charging up a Solar Beam, while Poliwrath blasted a Hydro Pump at it. There was a bit of confusion from Charizard, but he took Yosuke’s directions with vigor, spewing a deadly Fire Blast at Mewtwo from the ground. 

It was working, or at least it  _ looked _ like it was working. Mewtwo was stopping or reflecting most of the attacks, but the constant barrage of attacks from all sides meant that  _ some _ attacks were getting through. The legendary birds lived up to their names, each of their attacks that actually connected sending Mewtwo staggering backwards. Articuno’s ice would freeze part of the creature’s body only for Moltres or Charizard’s attacks to immediately thaw it, causing the Mewtwo to shout in pain. Zapdos managed to hit the creature hard enough with a thunderbolt to momentarily stun it. And while not nearly as powerful, Poliwrath’s constant stream of Hydro Pump was certainly at least an annoyance. 

Perhaps that was the reason that the Mewtwo targeted Poliwrath first. With a scream of pain and frustration, the Mewtwo managed to deflect a thunderbolt and send it crashing down toward Poliwrath. Except that Yosuke’s Venusaur threw himself in the way instead, absorbing the errant thunderbolt with a defiant roar. And then his wonderful, amazing Venusaur sent a Solar Beam slamming into the Mewtwo. The mighty attack pushed the Mewtwo back several feet and actually forced it to land on the ground. It again screamed in frustration and began to charge up some kind of psychic attack, but before it could unleash the psychic energy it had to go back on the defensive as several attacks all flew towards it. 

The battle raged on, and it was becoming more and more obvious that the Mewtwo was starting to get tired. The near constant guarding and the damage caused by the attacks it couldn’t defend against were clearly starting to take a toll on the creature. Yosuke considered having Venusaur move close enough to it to use Sleep Powder or Stun Spore.

Of course, he should have known better. The Mewtwo eventually let out a scream of frustration that boomed so loudly in their heads that both Yu and Yosuke were forced to their knees, to say nothing of their Pokémon. Yosuke could only watch in horror as the Mewtwo shot into the air and physically slammed into Moltres, battering the bird Pokémon into the floor below with a powerful burst of psychic energy. He systematically tore his way through the stunned Zapdos and Articuno in a similar fashion, the three birds returning to their Pokéballs, defeated.

And then the Mewtwo set his glowing eyes on  _ them _ . Not the three other Pokémon, but the two defenseless humans commanding them. Yosuke suddenly understood how Lance and the Elite 4 had ended up nearly unconscious on the cave floor as a blast of psychic energy shot towards the two of them. 

But of course, their Pokémon were having none of that. Despite being weak to psychic, Venusaur and Poliwrath charged into the path of the psychic blast, taking it head on. Charizard, with neither Yosuke nor Yu directing him, flew up at the Mewtwo and managed to catch it so off-guard that it was forced into a grapple with the fire lizard. 

“We’re running out of options,” Yosuke said, watching as his Venusaur and Poliwrath collapsed and returned to their Pokéballs. With a grimace, Yu sent out his Crobat.

“Go find help,” he told her, and the little bat tearfully nodded and flittered away. 

“The birds were my last ditch option,” Yu admitted. 

“All I’ve really got left is Toxicroak,” Yosuke groaned. He slammed his hands down onto the floor of the cavern. “Damn it! How can this thing be so powerful?!” Yosuke snapped his head up when something that turned out to be Yu’s Charizard crashed into the floor of the cavern just in front of where the two of them were kneeling. Mewtwo loomed above them, floating in that purple energy. It was obvious that the fight had severely weakened the creature, and wrestling with Charizard had especially taken a toll on it. They could see it heaving for breath for the first time, and there were gashes and burn marks and bruises all over it.

“Leave me in peace, humans!” it bellowed, throwing a Psychic attack at the two of them. Charizard was down and hadn’t quite fainted yet, but there was no way he would be throwing himself in front of them like Yosuke’s beloved Venusaur and Poliwrath had. No, this psychic blast was going to hit them both. Or, at least, it was going to hit  _ one _ of them. With a defiant cry, Yosuke threw himself at Yu and tackled the silver-haired trainer out of the way. Yu shouted his name in panic, and that was the last thing Yosuke heard before a torrent of pain overcame him. The attack slammed into him both physically and mentally, overwhelming him in an instant. He knew he hit the ground but didn’t feel it. 

All Yosuke could hear was a painfully loud ringing as his vision and consciousness slowly swam away from him. From his vantage point he could see part of the Mewtwo as it hovered above them. He saw Yu’s face above him and could tell he was speaking, but couldn’t make out the words. He saw Yu’s eyes widen and watched him look up toward the Mewtwo in a blind panic. Then he saw a red light take the shape of one of the Pokémon he’d been raising. He’d traded with a friend in Kalos for it, and had been eager to see what the little frog would evolve into. It was a wilful little thing, often coming out of its Pokéball, as if Yosuke were some novice trainer that couldn’t command an underleveled little Pokémon. Chie had suggested that the Froakie actually liked him a lot and just wanted to be around him. 

What a time for his Frogadier to come out of its Pokéball. Seeing the determined look on his froggy face snapped Yosuke out of the stupor he’d been in. He sat bolt upright as his vastly underleveled Frogadier lept in front of the two of them, fully intent on shielding them from the psychic blast that was heading straight at them.

“Frogadier, no! You’re too underleveled, this could  _ kill _ you!” Yosuke gasped. His Frogadier looked at him over his shoulder. And then, something truly unexpected happened. Just before the blast hit, Frogadier glowed with the bright white light of evolution. Yosuke had no idea what Frogadier actually evolved into. He intentionally hadn't looked into it, wanting it to be a surprise. Well, it  _ certainly _ was a surprise. The new form was taller, lankier, with a darker blue body and some kind of pink...scarf? Wait, was that its  _ tongue _ ?! It looked kind of like a ninja, Yosuke thought.

The psychic blast hit, and the ninja frog just… pushed it away, to Yosuke’s utter shock. Yu’s also, if the way he was gaping at the frog was any indication. The ninja frog did something with his hands that produced what looked like a gigantic throwing star made of water, which he threw at the Mewtwo. The Mewtwo dodged, of course, but that gave the frog time to leap into the air straight at the Mewtwo. The Mewtwo readied an attack, but the ninja frog suddenly vanished in a plume of darkness, reappearing just above and behind the Mewtwo. The frog lashed out with a fist cloaked in dark energy, striking the Mewtwo and making it scream out in pain, not mentally but from its actual, physical mouth. The frog then latched onto the Mewtwo’s back, arms and legs restraining the Mewtwo and its tongue wrapping around the Mewtwo’s neck. The Mewtwo screamed in rage and emanated a psychic blast from its body, but the ninja frog was completely unaffected.

This was their chance. Yosuke dug an Ultra ball out of his backpack and flung it up at the Mewtwo, desperately hoping it would stay in the ball. The Mewtwo used another blast of psychic energy to deflect the ball, to his dismay. Yu tried throwing a ball of his own, only for the same thing to happen.

“We need to weaken it more,” he said. “But I don’t have any Pokémon left that are nearly strong enough." Yosuke nodded, thinking about the little Sobble he had buried at the bottom of his bag. It would never be able to do enough damage. Then, in a moment of clarity, he had the answer.

“Yu, Lance gave you a potion!” he blurted out, and Yu’s eyes widened. He turned to Yosuke with a nod and rushed over to where his Charizard was, miraculously, still conscious. Yosuke dug in his bag and withdrew his one remaining Max Revive. Praying he was making the right decision, he popped it open and pressed it against the button on his Venusaur’s Pokéball. 

Charizard staggered to his feet and with a mighty roar, he rocketed up at the Mewtwo.

“Use fire! Frogadier should resist it!” Yosuke called out, and Charizard looked to him with a nod. He opened his mouth and a peal of flames slammed into the Mewtwo and, consequently, Frogadier’s evolved form. The frog held on, and although looked like he was trying hard not to let Yosuke know, he was definitely in a lot of pain. Yosuke just hoped he could hold on.

“Venusaur, I choose you!” Yosuke said, sending out his most trusted Pokémon. The enormous frog plant appeared with a roar of his own. Yosuke pointed at the Mewtwo. “Put that thing to sleep!” he ordered. Venusaur nodded and galloped to a spot right beneath where the aerial battle was taking place. As soon as Charizard let up on the flames, Venusaur’s petals and leaves rustled and a cloud of yellow dust flew up and coated the Mewtwo and the ninja frog. With a defeated groan, the Mewtwo’s eyes slid shut and he fell straight out of the air. The ninja frog also fell asleep, his arms and tongue going slack. The Mewtwo fell forward and the frog fell back, landing harmlessly on Venusaur’s back. The Mewtwo slammed face-first into the cavern floor. 

Yosuke and Yu both readied Ultra Balls, only to stop and look at each-other.

“You capture it, Yosuke,” Yu said. “You did all the hard work.”

“There’s no way I can train this thing, Yu!” Yosuke protested. “You’re training the legendary birds, you should catch it.”

They both stared at each-other for a second, before grinning.

“How about this? Which ever ball catches it will determine who has to take care of it,” Yu said. Yosuke nodded. They approached the sleeping creature.

“On the count of three,” Yosuke said. They counted down, and threw out their Pokéballs.

The cave went dark as soon as the Mewtwo was captured. 

“I didn’t actually see which ball captured it,” Yosuke said. “Did you?”

“Nope,” Yu said, with a sigh. He whistled at his Charizard. “Charizard, I know I never taught you Flash, but can you light up the cave for us?” Charizard grunted in affirmative, the flame on his tail surged, and the cave was bathed in a yellow glow that made it look like an entirely different place than it had mere minutes prior. That had been the Mewtwo’s influence, Yosuke was positive. 

“Oh, you can have this back now,” Yosuke said, handing over Charizard’s Pokéball. They approached where the two Ultra balls were sitting side-by-side, one containing the most powerful Pokémon either of them had ever faced, and the other empty. Yosuke reached down and picked one of them up, and was startled when his Pokédex made a ‘ping’ sound, indicating that there was a new entry. Yu picked up the other ball, curious.

“Maybe it’s on a delay, and it’s gonna tell me what Frogadier evolved into,” Yosuke said. He fished the little red computer out of his bag and flipped it open.

There were two new entries. One was for Mewtwo, which displayed a picture of the Mewtwo and the rest of the entry was nothing but question marks, even the name field. The other was labeled ‘Greninja’. 

“I guess I caught Mewtwo,” Yosuke said. “And Frogadier evolved into Greninja. Oh, and he’s part Dark. That explains why Mewtwo’s psychic attacks weren’t doing anything to him.”

“He saved us,” Yu said, with a grin. “You saved us, Yosuke.”

“Hey hey hey, Partner, I’m not about to take all of the credit!” Yosuke protested. Yu smiled fondly at him. Yosuke smiled back, and Yu leaned over and kissed him. Just like that, with no warning or anything. Yosuke made a startled noise into the kiss, but quickly melted into it. They kissed long enough that Greninja woke up. His confused noise startled both of them and they broke apart, both staring at each-other in shock. Yosuke’s face went red and Yu’s matched him not long after as the two of them started to stammer at each other.

“I— Yosuke, I’m sorry, I don’t know what came over me,” Yu said.

“Um, I, you, uhh…” Yosuke replied. They both seemed to realize how close they were to each other and both stepped back, embarrassed. Greninja made another curious noise and they both turned to look at him, as if suddenly realizing that they were still in that cave, in plain view of their Pokémon. 

Yosuke suddenly felt something oddly like Venusaur’s vines press against his back, shoving him into Yu who was also being shoved forward by Charizard. They collided with each-other, arms going around the other instinctively.

“I guess it was the adrenaline from surviving such a difficult battle, Yosuke,” Yu said, pointedly not looking at him. He was still blushing. It was… cute. 

“I...didn’t mind,” Yosuke finally managed to say. Yu looked at him, and he could see hope and fear both on his face. “I’ve… I’ve liked you for a long time, actually, Yu.”

“You too?” Yu asked, and the hope seemed to win out. He grinned. “I think our Pokémon figured it out before we did, huh?” Yosuke laughed. Venusaur’s vines had circled around the two of them, holding them gently but firmly in place. Charizard was still leaning his massive head against Yu’s back. 

“We did it, Partner. We saved Kanto,” Yosuke said, and this time Yu laughed. He wasn’t much taller than Yosuke, maybe an inch or two, but he still had to lean down a little to press his lips against Yosuke’s again. Yosuke gratefully kissed back, tightening his already tight hold on Yu’s shoulders. At some point during their frantic making out the vines retreated and Charizard backed away, but neither of them noticed. They barely noticed when Crobat returned some time later with a gaggle of gym leaders.

Cerulean Cave was declared a disaster zone. It was likely going to take years before it was safe enough for trainers to enter, even Master trainers like Yu and Yosuke. When asked if either of them wanted the title of Champion back, they both declined. 

Yosuke’s little brother, Teddie, ended up temporarily taking over as the Viridian City gym leader as Yosuke suddenly found himself very, very busy. Professors from around the world arrived at the Indigo Plateau to study Mewtwo. Blaine and Mr. Fuji were also summoned for questioning by Lance and the Elite 4. Yosuke learned that it was indeed a clone of Mew that had been the subject of horrific scientific experiments. Blaine, Mr. Fuji and Giovanni of Team Rocket had all overseen the project, the goal of which had been to create the most powerful Pokémon the world had ever known. They had succeeded, but the creation had easily been able to break out of its containment, fleeing and causing the mansion on Cinnabar Island to burn down in its wake. Blaine and Mr. Fuji, ashamed of what terrible things they had done to the experiment, had vowed never to speak of it again and gone back to their former lives... until they were summoned, of course. Giovanni and Team Rocket, however, had pursued the creature. Their chase had ended at Cerulean Cave, where Mewtwo had managed to wall itself off and hide. 

With a literal battalion of steel and dark type Pokémon at the ready, Yosuke called Mewtwo out of its Pokéball to ask it some questions. Mewtwo now had a grudging respect for both Yosuke and Yu and decided to cooperate with them… and only them. 

“I grew tired of hiding,” Mewtwo told them after they asked why it had suddenly appeared after being dormant for so long. “I grew weary of the darkness. I decided to try to look for somewhere else to be where I wouldn’t be bothered by humans. At the first sight of the humans outside of my cave, I panicked and accidentally blew up the cave entrance.” 

“And so the Elite 4 and Champions were called in,” Yu said. “Makes sense.”

“Tell me, Yosuke,” Mewtwo said, and Yosuke nearly jumped out of his skin hearing the Mewtwo address him by name. “Do you intend to keep me inside of this capsule?” 

“Not all of the time,” Yosuke said. “But it’s safer for you and all of us if you stay in it at least some of the time.” 

“So I am to be bound to this thing then, and to you,” Mewtwo sighed. “Very well. You seem like a benevolent master at least.”

“I won’t let them hurt you,” Yosuke said, glaring around at the Professors and scientists in the room. “But if you don’t mind, I know a lot of them would like to study you.” Mewtwo looked at him, concerned. “You know, measure your height, your weight, see what kind of attacks you can do… nothing like what those scientists before were doing, I swear it.”

“I… suppose I could deal with that,” Mewtwo said.

“And, y’know, if you don’t mind, once we're done here we could do some travelling together. There are some places I’d like to visit, and something tells me you want to see the rest of the world too,” Yosuke offered. He startled just a little when he felt a hand slip into his, but calmed down when he saw it was connected to Yu. He still blushed in surprise.

“I’ll show you all the best places in Johto, if you want,” Yu offered. Yosuke nodded with a smile. “Mt. Silver is beautiful this time of year, and I’m sure Mewtwo would enjoy some fresh air after being cooped up in that cave for so long.” 

“Sounds good, Partner,” Yosuke replied. Yu smiled, and then he laughed.

“It’ll just be you, me, and our psychic purple cat son,” he said, and Yosuke blushed bright red. Mewtwo looked startled as well… but neither of them actually protested.

**Author's Note:**

> Please let me know what you guys think! I enjoyed writing this little AU, I might write them more often with the boys...


End file.
